1. Field of the Invention
The present invention relates to a vapor vent control valve arrangement for a fluid tank. More specifically, a slenoid operable valve is disclosed, which valve utilizes a spring-biased actuation means and a resilient member to provide a safety function. A specific embodiment is taught for an automobile fuel tank application.
2. Description of the Prior Art
A variety of control circuits and apparatus providing communication between a fuel tank and a vapor storage system or vapor consumption equipment are taught in the prior art. Vapor consumption equipment generally refers to injection or aspiration of captured vapors into an air-fuel mixing device for an automobile engine. Indicative of a cannister storage system is that shown in the Chassis and Body Service Manual for the 1982 Buick at page 6e 1-12 and 1-13. In the drawing illustrated therein, a vapor storage cannister is connected through a line to the top of a fuel tank. The single control element illustrated in the schematic drawing is a vent restrictor in the conduit between the fuel tank and cannister. Vapors from the fuel tank are transmitted to the vapor storage cannister, which is subsequently evacuated or purged to the air-fuel mixer during engine operation. Purge of this vapor storage cannister, which is charcoal filled, is provided through a purge solenoid which may be responsive to engine temperature or other operating parameters. A diagramatic view of the charcoal cannister is provided at FIG. 6e 1-16a of the aforementioned manual. The vent restrictor does not provide a seal means as a precautionary measure and is continually evacuating the fuel tank.
U.S. Pat. No. 3,586,016--Meyn discloses a control valve for a tank filling and evaporation arrangement which includes a buoyant member for the fuel level having a permanent magnet available to actuate a reed switch. The reed switch is in series with a pressure switch and a solenoid valve controlling flow between the fuel tank and the vapor storage means. The pressure switch is closed when the buoyant member is a lowered or rest position. The reed switch, which is in parallel with the fuel level and tank attitude sensing means, remains closed when the attitude sensing means is in the reference position. In addition, the pressure switch will close to complete the solenoid circuit only if the tank vapor pressure is high enough to actuate this pressure switch.
A similar system is disclosed in U.S. Pat. No. 3,586,015--Kitzner. However, the Kitzner patent includes a spherical weight movable on a ramp to open the reed switch in response to changes in tank attitude.
U.S. Pat. No. 3,200,214--Aubert discloses a magnetically-actuated reed switch. This reed switch is in a flow control device with a movable magnetic means therein.
U.S. Pat. No. 3,242,937--Morin teaches an air vent for a fuel tank with a set of adjustable floats which are raised by excess fuel to close a needle valve. The needle is also moved by an adjustable plate and lever assembly which rotates when the tank is tilted.
The above-described art discloses valve closing means generally utilizing magnetic operators and float control means in alternative series and/or parallel circuits. The invention disclosed herein requires only a single magnet, utilizes a parallel switch circuit in the series circuit, has a solenoid operator providing a relief valve arrangement in addition to a controllable valve, and a predetermined pressure level in the tank is not required to complete the circuit.